<p>Howard Gardner’s Multiple Intelligences (MIs) theory has garnered significant attention in recent years. However, the effects of MI-informed tasks on various dimensions of second language (L2) learning require further investigation, particularly within the English as a Foreign Language (EFL) context in Iran. Thus, this study explored three key Objectives: First, how MI-informed tasks influence EFL learners’ willingness to communicate (WTC). Second, how these tasks impact academic engagement among EFL learners. Third, whether MI-informed tasks significantly enhance EFL learners’ academic success. For the first two objectives, 20 intermediate-level EFL learners were purposively sampled and invited to participate in semi-structured interviews. For the third objective, 40 intermediate-level EFL learners, aged 18 to 23, were selected from two intact classes at a private language institute and were randomly assigned to a control and an experimental group. The participants underwent a pretest, interventions, and a posttest. The results of the thematic content analysis disclosed that MI-informed tasks positively affected EFL learners’ WTC through engagement and active participation, confidence and self-efficacy, peer interaction and collaboration, variety and engagement in learning activities, and sense of autonomy and empowerment. Additionally, the qualitative results revealed that MI-informed tasks substantially enhanced the EFL learners’ engagement via active participation and involvement, enthusiasm and motivation, collaboration and peer interaction, variety and novelty in learning experiences, and sense of ownership and autonomy. Furthermore, independent <i>t</i>-test results showed that the experimental group outperformed the control group in terms of academic success. The implications are discussed for various EFL stakeholders.</p>